David Ng said about 4 years ago on Working with Internationalization :
When I use i18n-tasks normalize, I got message

warning: parser/current is loading parser/ruby26, which recognizes
warning: 2.6.5-compliant syntax, but you are running 2.6.3.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.

How could I get around this parser issues ?